Method of creping paper using air jets



Aug"v 1964 R. R. BORDEN 3,145,136

METHOD OF CREPING PAPER USING AIR JETS Filed Oct. 20, 1961 INVENTOR ROGER R. BORDEN ATTORNEY United States Patent ()flice 3,145,136 Patented Aug. 18, 196% 3,145,136 METHOD OF CREPING PAPER USIN G AIR JETS Roger R. Borden, Worcester, Mass, assignor to Lodding Engineering Corporation, Auburn, Mass, a corporation of Massachusetts Filed Oct. 20, 1961, Ser. No. 146,637 1 Claim. (Cl. 162-411) This invention relates to a new and improved supersonic air doctor, and the general nature of the invention resides in the provision of an elongated pipe which extends across a roll, the surface of which is to be doctored, this pipe being provided with a series of closely spaced nozzles in a row, each nozzle having a special bore which provides a jet of air of supersonic velocity directed against the surface of the roll for greatly increased effectiveness both in stripping paper from the surface of the roll and also in the manufacture of creped paper.

The effect of the supersonic jets of air is provided through the use of special nozzles, each nozzle having a converging-diverging bore which increases in diameter from a narrow throat to the exit or outer end directed toward the surface to be doctored.

It has been found, for instance, with a certain size of pipe and certain sizes of bore diameters for the nozzles, a hundred pounds per square inch air pressure in the pipe will provide a greatly increased speed of flow of the air to a supersonic velocity, which represents approximately a one-third increase in velocity or more over that which is possible with ordinary nozzles, so that with the present invention the effectiveness of the stripping action is greatly enhanced and by reason of the increased velocity it has been found that paper may be creped by use of the air jet disclosed herein.

The advantages of air jets over mechanical doctor blades are well known to those skilled in the art but briefly the air may be easily controlled and by avoiding the use of the mechanical blade, the roll surface is not worn or damaged, and the sharpening of the blades is avoided, and little or no wear or damage on the air nozzles is found even after long periods of use.

The invention further relates to arrangements and combinations of parts which will be hereinafter described and more particularly set forth in the appended claim.

Reference is to be had to the accompanying drawings, in which:

FIG. 1 is a view in rear the invention;

FIG. 2 is a sectional view on on line 2-2 of FIG. 1;

FIG. 3 is a view in elevation showing the exterior aspect of the nozzle, this view being on an enlarged scale and looking in the direction of arrow 3 in FIG. 2;

FIG. 4 is a section on line 4-4 of FIG. 3; and

FIG. 5 is a diagrammatic view illustrating making creped paper by use of the air jet.

In carrying out the present invention, the same is shown as applied in a more or less known manner to a set of rolls, for instance calender rolls, including an upper soft cover roll 40 and a lower chilled iron roll 12. The paper web travels over the soft cover roll into the nip between the soft cover roll and the chilled iron roll and has to be separated from the soft cover roll as it tends to cling to it, this being done usually by doctor blades. In the present case the supersonic air jet doctor is utilized for this purpose.

In order to provide the air doctor of the present invention, an air supply say of one hundred pounds per square inch is connected to for instance a pipe 14 which is provided with a valve 16 operable to be opened and closed in any way desired and connected to the doctor elevation showing a form of an enlarged scale, taken nozzle pipe 18 which extends across the machine, i.e., along the rolls. A valve 20 which is normally closed in the operation of the machine may be provided in the position shown in FIG. 1.

The pipe 18 is provided with the new and improved nozzles at closely spaced intervals and these nozzles are generally indicated at 22.

By the use of the nozzle shown herein, the velocity of the air is greatly increased about one-third and actually becomes supersonic so that when it strikes the surface of the cylinder it is much more effective than would otherwise be the case but does not injure the surface of the roll any more than would an ordinary jet from an ordinary nozzle.

This great increase in speed is obtained through the fact that the bore of each nozzle which is indicated at 24 gradually increases in diameter from a minimum at the throat 26 near the entrance to the bore (see FIG. 4), to a maximum at the extreme outer end of the bore as at 28. A small enlargement in the opposite direction is provided at the extreme inner end of the nozzle as at 350, this forming the converging-diverging bore having the smallest diameter at the throat 26.

It will be seen that the bore 24 is substantially conical and that the volume of air is restricted in the throat area as, being allowed to increase from the area 26 to the exit at 28, and this in combination with the enlargement at 30 provides the supersonic velocity effect of the air stream. It is pointed out that with a one-inch pipe and with the nozzle approximately three-eighths of an inch long and increasing from .040 approximately along a four degree angle, one houndred pounds per square inch provide the necessary supersonic velocity; however, these particular figures are of course greatly variable and the supersonic velocity may be attained with different dimensions. For instance, a smaller pipe with a smaller nozzle bore will attain the supersonic velocity at a pressure less than one hundred pounds per square inch, and variations of this kind can be made without departing from the scope of the invention.

Referring to FIG. 5, there is here shown the jet arranged with respect to the surface of the creping drier 49 at an angle which is approximately twenty-five degrees with respect to a tangent to the surface of the creping drier at the point where the jet stream impinges upon it serving to strip the paper 42 from the creping drier and also at the same time creping it, so that it will be seen that the present invention provides a jet stream at a high enough velocity to manufacture creped paper. In FIG. 5 the apparatus other than the air jet is substantially conventional, there being shown a felt 44 which passes over the rolls 46, 46, carrying the web 48 with it and transferring the same to the creping drier 40 from which it is stripped by the air jet as above described. Otherwise the arrangement of FIG. 1 can be used.

It will be seen that this invention provides a new and improved high velocity air jet which can be used as described as a stripping doctor for a paper web and also for the creping of paper.

It is pointed out that the nozzles in the pipe shown all operate substantially instantaneously in forming the supersonic row of jets because of the fact that the air under pressure fills the entire pipe to an equal degree prior to the initiation of the supersonic action described, and once the pressure is reached in the pipe it of course extends from end-to-end thereof and causes all of the nozzles to be operated substantially simultaneously to provide the supersonic jet.

Having thus described my invention and the advantages 3 thereof, I do not wish to be limited to the details herein disclosed, otherwise than as set forth in the claim, but what I claim is:

The method of making creped paper comprising traveling a web of paper over a creping cylinder and applying thereto a stream of air at a supersonic velocity which impinges the surface of the creping cylinder with a supersonic velocity suflicient to crepe the paper and strip it from the creping cylinder, wherein the angle of the stream of air relative to the cylinder surface is approximately 25 from a tangent to the cylinder surface Where the stream strikes it.

References Cited in the file of this patent UNITED STATES PATENTS Paradise Mar. 31, Pipe Apr. 16, Snow Oct. 4, Snow et al. June 10, Hibner Feb. 11,

FOREIGN PATENTS Germany May 21, Canada Apr. 17, Germany Feb. 26,

Great Britain June 10, 

